This invention relates to a fluid flow control valve for use with highly abrasive fluids in low fluid level wells.
In many operations performed in wells it is desired to pump fluids down through a string of tubing or conduit into a subsurface formation intersected by the well bore. In many such operations it is desirable to be able to control the flow of fluids in the string of tubing for a wide variety of purposes by placing a valve therein.
In many areas wells contain weak formations which will allow unlimited fluid flow thereinto unless the flow of the fluid is controlled. These weak formations typically will accept the flow of fluid in a tubing string due to the hydrostatic pressure of the fluid column in the tubing string without any pressure increase from pumping operations.
In these instances, a valve is used in the string of tubing at a point therein near the weak formation to control the flow of fluid from the string of tubing. Typically, these valves can be preset to open and close at specific tubing pressures to allow control over the pumping of fluids into the weak formation.
Typical prior art valves used in string of tubing are shown in U.S. Pat. Nos. 2854929, 2888080, 3847223, 4274490, 4399871, 4586569, and 4957167. While these types of valves are satisfactory for controlling the flow of fluids pumped into a well, when pumping highly abrasive fluids through the valves, various parts of the valve can be easily abraded thereby causing the valve to have either diminished flow control ability or to lose control of fluid flow completely.